PROBLEM TO BE SOLVED: To provide a trocar with an introducer sheath, eliminating the risk of a trocar needle mis-puncturing a front living body wall, excelling in operability in operation, and safe and easy to use.SOLUTION: The trocar needle 6 is regulated to be stored in a needle cover sleeve when not in use, and released from regulation by pressing a push button 4 with the fingertip when in use. Under pressure caused by puncture, the needle cover sleeve retreats into a position where the needle tip 6a of the trocar needle projects, and the retreat state is maintained. When the trocar needle reaches a body cavity and the pressure is reduced from the predetermined value, the needle cover sleeve is returns into a position where the trocar needle is stored, and the trocar needle 6 is stored in the needle cover sleeve. After puncture, the trocar is pulled out leaving the introducer sheath, and the introducer sheath is removed after inserting a catheter.
